001: /*
002: * $Header: /home/cvs/jakarta-tomcat-4.0/catalina/src/share/org/apache/catalina/Pipeline.java,v 1.4 2001/07/22 20:13:30 pier Exp $
003: * $Revision: 1.4 $
004: * $Date: 2001/07/22 20:13:30 $
005: *
006: * ====================================================================
007: *
008: * The Apache Software License, Version 1.1
009: *
010: * Copyright (c) 1999-2001 The Apache Software Foundation. All rights
011: * reserved.
012: *
013: * Redistribution and use in source and binary forms, with or without
014: * modification, are permitted provided that the following conditions
015: * are met:
016: *
017: * 1. Redistributions of source code must retain the above copyright
018: * notice, this list of conditions and the following disclaimer.
019: *
020: * 2. Redistributions in binary form must reproduce the above copyright
021: * notice, this list of conditions and the following disclaimer in
022: * the documentation and/or other materials provided with the
023: * distribution.
024: *
025: * 3. The end-user documentation included with the redistribution, if
026: * any, must include the following acknowlegement:
027: * "This product includes software developed by the
028: * Apache Software Foundation (http://www.apache.org/)."
029: * Alternately, this acknowlegement may appear in the software itself,
030: * if and wherever such third-party acknowlegements normally appear.
031: *
032: * 4. The names "The Jakarta Project", "Tomcat", and "Apache Software
033: * Foundation" must not be used to endorse or promote products derived
034: * from this software without prior written permission. For written
035: * permission, please contact apache@apache.org.
036: *
037: * 5. Products derived from this software may not be called "Apache"
038: * nor may "Apache" appear in their names without prior written
039: * permission of the Apache Group.
040: *
041: * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
042: * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
043: * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
044: * DISCLAIMED. IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
045: * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
046: * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
047: * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
048: * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
049: * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
050: * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
051: * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
052: * SUCH DAMAGE.
053: * ====================================================================
054: *
055: * This software consists of voluntary contributions made by many
056: * individuals on behalf of the Apache Software Foundation. For more
057: * information on the Apache Software Foundation, please see
058: * <http://www.apache.org/>.
059: *
060: * [Additional notices, if required by prior licensing conditions]
061: *
062: */
063:
064: package org.apache.catalina;
065:
066: import java.io.IOException;
067: import javax.servlet.ServletException;
068:
069: /**
070: * <p>Interface describing a collection of Valves that should be executed
071: * in sequence when the <code>invoke()</code> method is invoked. It is
072: * required that a Valve somewhere in the pipeline (usually the last one)
073: * must process the request and create the corresponding response, rather
074: * than trying to pass the request on.</p>
075: *
076: * <p>There is generally a single Pipeline instance associated with each
077: * Container. The container's normal request processing functionality is
078: * generally encapsulated in a container-specific Valve, which should always
079: * be executed at the end of a pipeline. To facilitate this, the
080: * <code>setBasic()</code> method is provided to set the Valve instance that
081: * will always be executed last. Other Valves will be executed in the order
082: * that they were added, before the basic Valve is executed.</p>
083: *
084: * @author Craig R. McClanahan
085: * @author Peter Donald
086: * @version $Revision: 1.4 $ $Date: 2001/07/22 20:13:30 $
087: */
088:
089: public interface Pipeline {
090:
091: // ------------------------------------------------------------- Properties
092:
093: /**
094: * <p>Return the Valve instance that has been distinguished as the basic
095: * Valve for this Pipeline (if any).
096: */
097: public Valve getBasic();
098:
099: /**
100: * <p>Set the Valve instance that has been distinguished as the basic
101: * Valve for this Pipeline (if any). Prioer to setting the basic Valve,
102: * the Valve's <code>setContainer()</code> will be called, if it
103: * implements <code>Contained</code>, with the owning Container as an
104: * argument. The method may throw an <code>IllegalArgumentException</code>
105: * if this Valve chooses not to be associated with this Container, or
106: * <code>IllegalStateException</code> if it is already associated with
107: * a different Container.</p>
108: *
109: * @param valve Valve to be distinguished as the basic Valve
110: */
111: public void setBasic(Valve valve);
112:
113: // --------------------------------------------------------- Public Methods
114:
115: /**
116: * <p>Add a new Valve to the end of the pipeline associated with this
117: * Container. Prior to adding the Valve, the Valve's
118: * <code>setContainer()</code> method will be called, if it implements
119: * <code>Contained</code>, with the owning Container as an argument.
120: * The method may throw an
121: * <code>IllegalArgumentException</code> if this Valve chooses not to
122: * be associated with this Container, or <code>IllegalStateException</code>
123: * if it is already associated with a different Container.</p>
124: *
125: * @param valve Valve to be added
126: *
127: * @exception IllegalArgumentException if this Container refused to
128: * accept the specified Valve
129: * @exception IllegalArgumentException if the specifie Valve refuses to be
130: * associated with this Container
131: * @exception IllegalStateException if the specified Valve is already
132: * associated with a different Container
133: */
134: public void addValve(Valve valve);
135:
136: /**
137: * Return the set of Valves in the pipeline associated with this
138: * Container, including the basic Valve (if any). If there are no
139: * such Valves, a zero-length array is returned.
140: */
141: public Valve[] getValves();
142:
143: /**
144: * Cause the specified request and response to be processed by the Valves
145: * associated with this pipeline, until one of these valves causes the
146: * response to be created and returned. The implementation must ensure
147: * that multiple simultaneous requests (on different threads) can be
148: * processed through the same Pipeline without interfering with each
149: * other's control flow.
150: *
151: * @param request The servlet request we are processing
152: * @param response The servlet response we are creating
153: *
154: * @exception IOException if an input/output error occurs
155: * @exception ServletException if a servlet exception is thrown
156: */
157: public void invoke(Request request, Response response)
158: throws IOException, ServletException;
159:
160: /**
161: * Remove the specified Valve from the pipeline associated with this
162: * Container, if it is found; otherwise, do nothing. If the Valve is
163: * found and removed, the Valve's <code>setContainer(null)</code> method
164: * will be called if it implements <code>Contained</code>.
165: *
166: * @param valve Valve to be removed
167: */
168: public void removeValve(Valve valve);
169:
170: }
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